Grandchildren's Longevity and Their Grandfathers' POW Trauma in the U.S. Civil War.

I document the transmission of a grandfather's net nutritional deprivation and psychosocial stress in young adulthood across multiple generations using the grandfather's ex-prisoner of war (ex-POW) status in the U.S. Civil War (1861-1865). Using a newly created dataset, I uncover an association between a grandfather's ex-POW status and the longevity after age 45 of his sons and male-line grandsons but not of his daughters, granddaughters, female-line grandsons, children-in-law, or grandchildren-in-law. Male-line grandsons lost roughly a year of life at age 45 (4% of remaining life expectancy) if descended from ex-POWs who suffered severe captivity conditions than if descended from non-POWs. If their grandfathers faced a less harsh captivity, male-line grandsons lost less than a year of life compared with those descended from non-POWs. I find that the grandfather's age at exposure and the grandson's education, as well as the son's and the grandson's poor late gestational conditions (proxied by season of birth), mediate this relationship. I rule out socioeconomic status, marriage and mortality selection, and cultural or psychological transmission from grandfathers to grandsons as explanations. I cannot rule out an epigenetic explanation.